WATCH: Stephen Hawking makes an emotional speech as he takes on the Ice Bucket Challenge

STEPHEN HAWKING, the world's most famous motor neurone disease sufferer, is the latest celebrity to take part in the ALS Ice Bucket Challenge.

The 72-year-old Cambridge academic started off his video with an emotional speech, urging everyone to support the Motor Neurone Disease Association (MNDA).

But due to catching pneumonia last year, the professor avoided an ice cold drenching thanks to his children who took the challenge in his place.

In the video, which was posted to YouTube, they can be seen laughing and screaming as the chilly water is poured over them by three helpers.

In his speech, Professor Hawking said: "I support the ALS ice bucket challenge in support of the MNDA, the Motor Neurone Disease Association.

"Because I had pneumonia last year, it would not be wise for me to have a bucket of cold water poured over me.

"But my children, Robert, Lucy and Tim, gallantly volunteered to take the challenge for me.

"I urge you to donate to the MNDA, to eliminate this terrible disease."

Stephen Hawking has taken part in the Ice Bucket Challenge [SG]

His family received the icy drenching on his behalf [SG]

I urge you to donate to the MNDA, to eliminate this terrible disease

Stephen Hawking

The professor then went on to nominate Lord Sainsbury, Chancellor of the University of Cambridge, Professor Sir Leszek Borysiewicz, Vice Chancellor of the University of Cambridge and Ian Blatchford, Director of the Science Museum, to take part in the worthy cause.

So far only Professor Borysiewicz has accepted Professor Hawking's challenge, with his video appearing online swiftly after his nomination.

Professor Hawking was diagnosed with motor neurone disease when he was just 21, with doctors predicting that he would have just two years left to live.

Despite his disease's rapid progression, he went on to astound the physics community with his scientific theories about space and the creation of the universe.

The ice bucket challenge has become an internet sensation, with thousands of people posting videos of themselves being drenched with icy water in the aid of raising money for the ALS Foundation.

Originating from the States, ALS is the American term for what is referred to as motor neurone disease in the UK.

Celebrities and famous folk across the globe have been soaked with freezing water for the good cause, including George Bush Jr., Cheryl Cole and Bill Gates.

The challenge was started by 27-year-old American Corey Griffin who wanted to raise money and awareness for motor neurone disease after witnessing his friend Peter Frates struggle with the crippling illness.

Tragically, Mr Griffin died last week after diving into the ocean from a building in Nantucket, Massachusetts.

So far the phenomenon has raised $94.3million (£56.8million) for the ALS Foundation in America and £2million for the MNDA in the UK.